The internet and other networks are based on a fundamental idea developed by the computer scientist Donald Watts Davies, who has died aged 75. He is not always given full credit for his contribution because Paul Baran, an American working at the Rand Corporation in California, had independently come up with the same idea. However, Baran was focusing on a way to restructure AT&T's telephone system. Davies was creating a data network, and the design of the Arpanet, the precursor of the internet, was changed completely to adopt his technique.